Tack, Harness, and Drawn Vehicles

As Tack, Harness, and Drawn Vehicles are historically vague and undefined in typical D&D play, we've provided additional descriptions to the items in question here for your use and consumption where applicable. 
Regarding drawn vehicles, if you are proficient with land vehicles, you are permitted to include your proficiency score in any check needed to control the vehicle in difficult situations. Generally speaking, a drawn vehicle requires enough mounts whose combined carrying capacity meets or exceeds the total weight of your vehicle and any inventory stored aboard it.